CHAPTER 



REPRODUCTION 

 OF ANIMALS 



iV. Y. Zoological Soc. 

 The buck has antlers. 



A', i'. Zoological Sac. 

 A doe with her fawn. 



Is the reproduction of an animal similar to that of a plant? Do all 

 animals reproduce in the same ivay? How does an animal develop 

 from the fertilized egg? How long does the development take? 



Seeds and eggs. The common form of propagation for higher 

 plants is through the formation of seeds, and for higher animals, 

 through the production of fertile eggs. INIost seeds are capable of 

 sprouting even after remaining at rest for a long time, sometimes 

 after many years. The germs in the seeds are destroyed, how- 

 ever, if the seeds become very wet and then dry again. 



The eggs of chickens and other birds are well known. The eggs 

 of fish and frogs are somewhat similar to those of birds, although 

 they are found in the water. Eggs of butterflies may frequently 

 be seen on plants. Those of water animals usually die if they 

 become dry. Birds' eggs have to be kept warm if they are to in- 

 cubate and to hatch. Those of injects may lie dormant over the 

 winter and develop in the spring. In general, eggs need more care 

 than seeds. In the case of many animals, the eggs must develop 

 soon after they are formed or they will die. They cannot live in 

 a dormant form for an indeterminate period of time as seeds can. 



Secondary sexual characters. In the lowest animals, it is often 

 quite impossible to distinguish the individuals that produce male 



WH. FITZ. AD. BIO. — 19 281 



